Automatic valves

ABSTRACT

An automatically operating shut-off valve has a valve body (12) with a weakened zone (15) about which the body will break, in the event the valve is subjected to a shock load. A valve seat (25) is formed within the body (12) and a valve member (29) is pivoted to move between an open position and a closed position, against the valve seat. The valve member is spring-urged to its closed position but is held in its open position by a crank (34) having a pin (35) bearing on a brittle glass rod (33). The valve will close whenever the rod (33) breaks, even if the shock load is only sufficient to crack the valve body, about the weakened zone.

This invention relates to an automatically-operating valve, intended toclose off a flow passage through the valve in the event that the valveis subjected to a significant shear force. In particular, but notexclusively, the invention is intended for use in connection with themounting of a forecourt liquid fuel dispensing pump, on to a supportingbase.

Fuel pumps for dispensing petrol or diesel fuel into the tank of a motorvehicle generally comprise a self-contained unit mounted on a base orplinth on a garage forecourt, the pump being connected by way of apipeline to an underground storage tank from which the fuel is drawnduring operation of the pump. Some fuel pumps operate simply by suction,so that there is a sub-atmospheric pressure in the pipe from theunderground tank to the pump, whenever the pump is in operation. Othersystems employ a pressure-feed system where fuel in the pipeline fromthe tank to the pump is under pressure, to ensure a uniform delivery offuel to the pump. This system may be employed when there is a relativelylong pipeline from the underground tank to the pump.

It is unfortunate that not infrequently, vehicles manoeuvring on agarage forecourt collide with a fuel pump and displace the fuel pumpfrom its proper position. In order to prevent significant fuel spillage(which could be most substantial in the case of a pressurised deliverysystem) it is the usual practice to fit a shear valve in the pipelinedelivering fuel to the pump, in the vicinity of the mounting of the pumpon to the base or plinth. An example of such a shear valve is shown inU.S. Pat. No. 3489160. This shear valve has a weakened zone so that ifthe pump is subjected to a lateral displacement, the valve will shearacross its weakened zone. An automatically-operating valve member withinthe shear valve then closes the delivery pipeline to prevent leakage offuel.

There is however a problem with the known design of shear valve; in theevent that a fuel pump is subjected to a minor impact which issufficient to cause the valve body to shear along its weakened zone butnot sufficient to displace the fuel pump significantly from its normalposition, it can happen that the valve member is not released so theflow passage through the valve body is not closed. As the valve body hassheared at its weakened zone, there results a significant leakage offuel.

It is a principal aim of the present invention to address theabove-described problem, and so to provide a valve wherein the closingof a flow passage through the valve can be assured in the event that thevalve body shears about a weakened zone provided therein.

According to the present invention, there is provided anautomatically-operating valve comprising a body defining a flow passageand having a weakened zone around that passage, a valve member mountedwithin the passage for movement towards a closed position where thevalve member closes the passage on one side of the weakened zone, springmeans urging the valve member to said closed position, a brittlefrangible link bridging the weakened zone, and a control mechanismbearing on the frangible link and controlling movement of the valvemember under the action of the spring means.

The shear valve of this invention will hereinafter further be describedparticularly with reference to its intended use with a forecourt petrolor diesel pump, though the valve may find uses in other industries--forexample in a chemical manufacturing plant.

It will be appreciated that in the automatically-operating valve of thepresent invention, the closing of the flow passage through the valvebody is controlled by a brittle frangible link which bridges theweakened zone. In the event that the valve body is subjected tosufficient force to shear the valve body at its weakened zone, thebrittle frangible link inevitably will also break, so freeing thecontrol mechanism to allow the valve member to move under the action ofthe spring means, thereby closing the flow passage. In this way, closingof the flow passage may be assured in the event that the valve body issubjected to a sufficient force to cause the valve body to shear at itsweakened zone, even if there is no significant movement between the twoparts of the sheared valve body.

Though the valve member could be arranged for linear sliding movementwithin the flow passage, it is preferred for the valve member to bepivotally mounted, for movement between an open position and said closedposition, the valve member not significantly impeding flow through theflow passage when in its open position. The valve member may be mountedon a shaft which projects externally of the body, in which case thecontrol mechanism may include a crank arm mounted on the shaft. Thecrank arm may have an abutment at or adjacent the end thereof remotefrom the shaft, which abutment may bear directly on the frangible link.In this way, upon the frangible link breaking, the abutment is no longerrestrained against movement by the frangible link so freeing the crankarm, and in turn allowing the valve member to move to its closedposition.

The frangible link preferably comprises a glass rod or tube. Such a linkshould be rigidly mounted on the valve body, to both sides of theweakened zone, whereby breakage of the link may be assured in the eventthat the valve body shears at that zone. In a preferred embodiment, apair of lugs upstand from the valve body, one to each side of theweakened zone, each lug defining a respective slot for receiving an endportion of the frangible link and the frangible link being clamped orcemented in position, in the slots.

Conveniently, the spring means is disposed externally of the body andacts on the shaft on which the valve member is mounted, or on the crankarm connected thereto.

In an improved form of automatically-operating valve of this invention,the control mechanism includes a fusible link which melts at apredetermined low temperature, thereby freeing the valve member to moveto its closed position under the action of the spring means.Alternatively, the frangible link could be arranged to soften, burst orbreak should the temperature in the vicinity of the valve risesignificantly, so freeing the valve member. Either arrangement may giveadded protection against fuel leakage, in the event of a fire in thevicinity of the valve.

The part of the body defining a flow passage having a weakened zone maybe formed as a separate unit removable from the remainder of the valvebody, in order to allow easy repair in the event that the valve has beensheared by an external force. For example, said unit may include a pairof external flanges disposed therearound, at each end of the unit, whichflanges may register with corresponding flanges formed on the remainderof the valve body and the respective flanges being bolted together in afluid-tight manner. Then, in the event that the valve shears, the boltsmay be released and the sheared unit removed from the remainder of thebody, for replacement by an unbroken unit.

In yet another improved form of this invention, a float is provided in acatchment tank or tray provided below the pump, which float is coupledto a trip mechanism associated with the control means of the valve,whereby the valve will close in the event that any significant quantityof liquid accumulates in the tank or tray. Thus, even if there should bea small leak of fuel, the valve of this invention may act to close offthe fuel supply to the pump.

Particularly when the valve is used for a forecourt fuel pump, it is anadvantage to provide a second automatically-operating valve within theshear valve body and arranged to close the flow passage through thevalve body on the side of the line of weakness opposed to that sidewhich is closed by the above-described automatically-operating valve.Such a second valve may comprise a simple non-return valve.Alternatively, that second automatically-operating valve may be ofsubstantially the same configuration as the first-mentionedautomatically-operating valve described above, the secondautomatically-operating valve also being controlled by the samefrangible link.

By way of example only, two specific embodiments of this invention willnow be described in detail, reference being made to the accompanyingdrawings, in which:

FIG. 1 is a side view of a known construction of automatically-operatingshear valve, such as is widely used for the pipeline feeding fuel to aforecourt fuel pump;

FIG. 2 is a diagrammatic sectional view through a first embodiment ofautomatically-operating valve constructed and arranged in accordancewith the present invention;

FIG. 3 is a detail view on a part of the valve of FIG. 2, taken in thedirection of arrow B marked on FIG. 2;

FIG. 4 is a sectional view through a second embodiment ofautomatically-operating valve of this invention; and

FIG. 5 shows a valve similar to that of FIG. 2, but including aremovable unit to facilitate repair.

Referring initially to FIG. 1, there is shown a known design of shearvalve for use in connecting the inlet pipe 10 of a forecourt fuel pumpto a pipeline 11 leading to the pump from an underground storage tank.The shear valve is intended to be installed at substantially the samelevel as the bottom of the fuel pump, where that pump is mounted on to abase or plinth. The shear valve comprises a body 12 which is internallythreaded at its lower end 13 and is directly screwed on to the end ofthe pipeline 11 from the tank. The upper end of the body 12 carries ahexagonal boss 14 which also is internally threaded, and into which isscrewed the inlet pipe 10 of the pump. Below the hexagonal boss 14, thewall thickness of the body 12 is greatly reduced, by means of a V-shapedannular groove 15 machined into the body 12, thereby defining a weakenedzone around the body. Thus, in the event that the valve body 12 issubjected to a significant shear force, shearing of the body may beassured across that groove 15.

A shaft 16 extends through the valve body 12, below the groove 15, andsupports internally of the body a valve member (not shown) which maymove to a position where the valve member closes the flow passagethrough the valve body, below the groove. 15, upon rotation of the shaftfrom the position shown. Crank 17 projects radially from the shaft andcarries a pin 18 at its free end, which pin is normally received in aslot 19 at the free end of an arm 20, pivoted to the body 12 above thegroove 15. A coil spring (not shown) is provided around the shaft 16, tourge the shaft to rotate in the direction of arrow A, and so to move thevalve member to its flow passage closing position.

It will be appreciated that upon shearing of the valve body, andprovided the relative movement between the upper and lower valve bodyparts is greater than some predetermined minimum, pin 18 will come freeof the slot 19 in arm 20, so allowing the shaft to rotate under theaction of the spring and thus closing the flow passage through thevalve. The problem arises when the shear valve is subjected to a shocksufficient to fracture the body about groove 15, but the pin 18 stillremains in the slot 19 of the arm 20, so that the valve member is notfreed to close the flow passage.

FIG. 2 is a diagrammatic cross-section through a first embodiment ofshear valve of the present invention and insofar as is approriate, likeparts with those of FIG. 1 are given like reference characters.Internally of the flow passage 27 within the body 12, there is formed anannular valve seat 25 below the groove 15, and a second annular valveseat 26 above the groove 15. Within the flow passage, an arm 28 isrigidly connected to the shaft 16, the arm 28 carrying a circular valvemember 29, movable upon rotation of the shaft 16 to the position shownin broken lines where the valve member seals against the valve seat 25and so closes the flow passage 27.

A non-return valve comprising a valve member 30 directly urged by aspring 31 is arranged above the groove 15, to cooperate with the secondvalve seat 26. This non-return valve may not be required for allapplications of the shear valve.

A pair of lugs 32 upstand from the valve body 12, one to each side ofthe groove 15. Each lug defines a slot in which is received a brittleglass rod 33, the rod being cemented at its two ends into the slots inthe two lugs, respectively.

Externally of the body 12, the shaft 16 carries a crank 34, the free endof that crank supporting a peg 35 which bears against the glass rod 33.A spring (not shown) is arranged to urge the shaft 16 to rotate in thedirection of arrow A. For example, the spring may comprise a coil springwound round the shaft 16 and having one end anchored to the body 12 andits other end connected to the crank 34.

As shown in FIG. 3, the crank 34 may be formed in two overlying parts 36and 37, the arm parts being linked together by means of a low meltingpoint adhesive whereby the arm parts will separate upon the temperaturerising to some predetermined value. As an alternative, the glass rod 33may be replaced by a brittle plastics material rod, which loses itsrigidity and strength when the temperature rises above somepredetermined value, so allowing shaft 16 to rotate.

During normal operation of the valve, the valve member 29 is in theposition shown in solid lines in FIG. 2 and is constrained there by thepeg 35 of the crank 34 bearing on the glass rod 33, notwithstanding theforce of the spring acting on shaft 16. Should the valve body besubjected to a shock sufficient to shear the valve body across groove15, the glass rod 33 inevitably will break so freeing crank 34 andallowing the valve member 29 to move to the position shown in brokenlines, in FIG. 2. This action will occur even should there be only avery small displacement of the two parts of the valve body, uponfracture of the body. Equally, should there be a fire resulting in atemperature rise, the two arm parts 36 and 37 will separate and allowvalve member 29 to move to a position where the flow passage 27 throughthe valve body is closed.

FIG. 4 shows a modification of the valve assembly of FIGS. 2 and 3 andagain like reference characters are used to indicate like parts. In thismodified form of valve, the non-return valve comprised by valve member30 and spring 31 is replaced by a second automatic valve described withreference to FIG. 2. Thus, this second valve comprises shaft 116, arm128, valve member 129 and crank 134, the peg 135 of crank 134 bearing onthe same glass rod 33 as does peg 35 of crank 34 of the first valve. Thefunction of this second valve assembly is precisely the same as that ofthe first-mentioned assembly and will not be described in detail againhere.

FIG. 5 shows a valve essentially similar to that of FIG. 2, but modifiedin order to facilitate the repair of the valve in the event that thevalve is subjected to a sufficient force to shear the valve across theweakened zone. In FIG. 5, like reference characters are used to denotelike parts with those of FIG. 2.

In this modified valve, the weakened zone 40 is formed in a separateunit 41, having at each end a respective external flange 42. The parts43 and 44 of the valve body to each side of the unit 41 are formed withcorresponding flanges 45 and 46, nuts and bolts 47 being used throughregistering holes in the flanges to secure the unit in position.

Pin 35, which acts against the link 33, is preferably made removablefrom arm 34, in order to facilitate servicing of the valve withoutbreaking the link.

The function of the embodiment of FIG. 5 is the same as that as has beendescribed above with reference to FIGS. 2 and 3 and will not bedescribed again here. When the valve is subjected to a sufficient forceto shear the unit 41 across its weakened zone 40, the nuts and bolts 47may be removed and the unit 41 then slid out from between the tworemaining body parts 43 and 44. Thereafter, a new unit may be slid intoposition and secured in a fluid-tight manner. It will be appreciatedthat this arrangement facilitates repair of the valve and there is noneed to dismantle any pipe-work to effect that repair.

I claim:
 1. An automatically-operating valve comprising a body defininga flow passage and having a weakened zone around that passage, a valvemember mounted within the passage for movement towards a closed positionwhere the valve member closes the passage on one side of the weakenedzone, spring means urging the valve member to said closed position, abrittle frangible link bridging the weakened zone, and a controlmechanism bearing on the frangible link and controlling movement of thevalve member under the action of the spring means.
 2. Anautomatically-operating valve as claimed in claim 1, wherein the valvemember is pivotally mounted within the flow passage.
 3. Anautomatically-operating valve as claimed in claim 2, wherein the valvemember is mounted on a shaft which projects externally of the body, andthe control mechanism includes a crank arm mounted on the shaft.
 4. Anautomatically-operating valve as claimed in claim 3, wherein the crankarm has an abutment at or adjacent the end thereof remote from the shaftwhich abutment bears directly on the frangible link.
 5. Anautomatically-operating valve as claimed in claim 1, wherein the controlmechanism includes a thermally-sensitive link which fails at apredetermined temperature.
 6. An automatically-operating valve asclaimed in claim 3, wherein the crank arm comprises two arm parts joinedtogether by a thermally-sensitive coupling which fails at apredetermined temperature.
 7. An automatically-operating valve asclaimed in claim 1, wherein the frangible link comprises a glass rod ortube.
 8. An automatically-operating valve as claimed in claim 1 and inwhich the valve member is mounted on a shaft which projects externallyof the body, wherein the spring force for the valve member is providedexternally of the body.
 9. An automatically-operating valve as claimedin claim 8, wherein the spring force is provided by a coil springmounted around the shaft and having one end anchored on the body.
 10. Anautomatically-operating valve as claimed in claim 1, wherein there is anannular valve seat within the flow passage to one side of the weakenedzone, and the valve member is spring-urged to a position where the valvemember engages the valve seat to close off the passage from the side ofthe valve seat further from the weakened zone.
 11. Anautomatically-operating valve as claimed in claim 1, wherein there isanother automatically-operating valve mounted within the passage, to theother side of the weakened zone in the body.
 12. Anautomatically-operating valve as claimed in claim 10, wherein saidanother automatically-operating valve comprises a spring-loadednon-return valve.
 13. An automatically-operating valve as claimed inclaim 10, wherein said another automatically-operating valve comprises afurther valve configured similarly to the aforesaidautomatically-operating valve and having a control mechanism bearing onthe same frangible link.
 14. An automatically-operating valve as claimedin claim 1, wherein the weakened zone is formed in a part of the bodyformed as a separate unit removable from the remainder of the valvebody.
 15. An automatically-operating valve as claimed in claim 14wherein said unit includes a pair of external flanges disposedtherearound at each end of the unit, for registering with correspondingflanges formed on the remainder of the valve body.